TBuffer Struc
  inbuf_MaxChars  Db  ?  ; How many symbols to enter
  inbuf_AllChars  Db  ?  ; How many symbols returned from INT 21H
  inbuf_Buffer    Db  128 Dup (?)
TBuffer EndS

.DATA
strDOSInput  TBuffer <?>

.CODE
  mov dx, offset [strDOSInput]  ; DS:DX points to TBuffer
  mov strDOSInput.inbuf_MaxChars, 8  ; Max. chars=7 + <ENTER>
  mov ah, 0Ah
  int 21h